System and method for measuring and recording skull vibration in situ

ABSTRACT

A method and apparatus for measuring and recording skull vibration in situ comprising a receiving means, a dental material capable of filling any gaps between the receiving means and the at least one tooth, the material capable of transmitting mechanical vibration within the dental bone conduction pathway to the receiving means; a transducer mounted into or unto the receiving means said transducer capable of transducing mechanical vibration within the dental bone conduction pathway into electrical signals; an extra-orally recordation hardware and software capable of receiving and processing said electrical signals from said transducer.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was supported by the National Institute of Deafness andCommunication Disorders (DIDCD) as provided for by the terms of1R41DC010082-01A1. The United States government has certain rights inthe invention.

FIELD OF INVENTION

This invention relates to a system or apparatus for measuring andrecording skull vibration in situ comprising a receiving means whichengages at least one maxillary tooth; a dental material which is capableof filling any gaps between the receiving means and the tooth (orteeth), and, is capable of transmitting mechanical vibration that existwithin the dental bone conduction pathway to the receiving means. Theinvention further comprises a transducer or sensor mounted into or untothe receiving means, said sensor being capable of transducing mechanicalvibration into electrical signals and an extra-orally disposed signalconditioner, computer, and other data recorder hardware and software forreceiving and processing electrical signals from the transducer.

BACKGROUND OF INVENTION AND DISCUSSION OF PRIOR ART

Reliable, non-invasive, low-cost, in situ measurement of skull vibrationfor the purpose of fitting a bone conduction hearing aid currently isnot possible. (Hodgetts W. E, Hakansson B. E. V, Hagler P, Soli S. Acomparison of three approaches to verifying aided Baha output. Internl JAudiology 2009 online.)

Skin placement of an accelerometer as a means to record skull vibration(specifically stimulation created by an implanted bone vibrator) wasattempted by Laitakari, et. al. (Laitakari k, Lopponen H, Salmivalli A,Sorri M. Objective Real Ear Measurements of Bone-conduction hearing AidPerformance. Scan Audiol 24:53-6, 1995. Laitakari K, Jamsa T.Computerized in-situ test for bone conduction hearing aids. ScandAudiol: 30: Suppl 52:79-80, 2001.)

This method uses a typical mechanical headband, like those associatedwith the oscillators for bone conduction audiometry, to couple theaccelerometer to the skull. Currently, it is acknowledged by experts inthe field that because vibrations of the overlying skin do not reflectunderlying skull vibrations, with the existing art, it is almostimpossible to measure skull vibration in living subjects. (Majdalawieh,Osama. Abstract to PhD Thesis, Dalhousie University, Halifax, Canada2008.)

Miller U.S. Pat. No. 7,447,319—“Method and system for externalassessment of hearing aids that include implanted actuators” focused onthe output of the hearing aid into an electrical/mechanical detector. Asimilar approach was taught by Leysieffer in 20020026091, “Implantablehearing system with means for measuring its coupling quality.” Both ofthese inventions were not concerned about the in-situ output in a livingskull, but rather the output into a device which functions more or lessas a “simulator device”.

The dental bone conduction pathway as used herein should be considered asub-pathway of the non-acoustic ‘bone conduction pathway” for soundtransmission to the hearing nerve. In the dental bone conductionpathway, sound perceived at the hearing nerve originates in structuresof the mouth and pharynx. Speech sounds and chewing sounds, for example,travel to the hearing nerve via the dental bone conduction pathway. Bycontrast, loud ambient helicopter noise that penetrates the skin overthe entire skull, neck, and body can be considered noise arriving at thehearing nerve via the bone conduction pathway. Similarly, standard boneconduction audiometry with skull stimulation at the mastoid or foreheaduses the bone conduction pathway as distinct from the dental boneconduction pathway.

The distinction between pathways is important because of anatomicaldifferences between the pathways. The bio-mechanical forces in thedental bone conduction pathway are variable and thus may create variableresults when compared to stimulation of structures elsewhere on theskull (at the mastoid or forehead for example). The large resonantchamber, anatomically named as the mouth and oropharynx, has itsresonance frequency altered by combinations of opening the mouth andmovements of the tongue, lips, and vocal chords (human speech). The mereact of biting changes the mechanical load on a top tooth bysignificantly increasing the load on that top tooth with the effectivemass (and variable biting force) from the lower jaw. Other pathwayentrances on the skull do not contain such variable effective mass orcompliant muscles and ligaments. Also, those other skull areas have farless voluntary muscle and compliant soft tissue (when compared to thetongue and cheeks of the mouth, for example), and more fixed chambers(e.g., frontal sinuses, mastoid air cells, external ear canal), and thusnecessarily have more consistent volumes, mechanical loads, and inputmechanical point impedances than do structures of the mouth and pharynx;that is, structures comprising the dental bone conduction pathway.

Unlike other methods to record (non-acoustic) skull vibration, theinstant invention uses the teeth as the site for measuring skullvibrations. Use of the teeth allows for greater sensitivity becausevibration sensing is via the dental bone conduction pathway having nooverlying skin, muscle, etc., to affect skull vibration. Equallyimportant, measuring skull vibrations through the teeth allows forrepeatable and reproducible tooth placement with a concomitantreplication of the (original) coupling force. The use of a toothmicrophone for speech recording and voice communication has been taughtby Brouns (Brouns J R. Experimental wide-band tooth-contact microphone.J Audio Engineer. 9:1:42, 1971), Mersky (U.S. Pat. No.5,455,842—Underwater Communication System), Anajanappa (U.S. Pat. Nos.7,269,266, 7,486,798), May (U.S. Pat. No. 5,579,284), Wieland (USPublished Patent Application No. 200090022351), and others. The toothcoupling methodologies, associated electronics, and recording softwarediffers substantially from the means and methods taught in thisinvention. Other art by Saadat and Alboufathi in Patent application20090281433, “Systems and methods for pulmonary monitoring andtreatment” teaches a means and method for recording breath sounds usingan intraoral sensor. That art differs from the instant invention in thatit requires an impression of the patient's dentition in order tofabricate and customize the tooth attachment means.

SUMMARY OF THE INVENTION

Accordingly, it is one object of the invention to provide an apparatusfor recording and measuring in-situ skull vibration comprising areceiving means which simultaneously engages the undercut area in thegingival one-third of at least one maxillary tooth and the interproximalarea between two adjacent maxillary teeth on both the buccal and lingualsurfaces, a dental material capable of filling any gaps between saidreceiving means and said at least one tooth, said material capable oftransmitting mechanical vibration within the dental bone conductionpathway to the receiving means; a transducer mounted into or unto thereceiving means said transducer capable of transducing mechanicalvibration within the dental bone conduction pathway into electricalsignals; disposed extra-orally, recordation hardware and softwarecapable of receiving and processing said electrical signals from saidtransducer.

It is another object of the invention to provide a method of placing atransducer in an apparatus for recording and measuring in-situ skullvibration, the method comprising the steps of selecting a receivingmeans that simultaneously engages the undercut area in the gingivalone-third of at least one maxillary tooth and the interproximal areabetween two adjacent maxillary teeth, engaging said tooth and teeth onboth the buccal and lingual surfaces; filling said receiving means witha dental material capable of filling any gaps between said receivingmeans and said at least one natural tooth, said material being capableof transmitting mechanical vibration within the dental bone conductionpathway to the receiving means and transducer; covering said transducerwith a sheath and placing the covered transducer into said receivingmeans; connecting said transducer via a wire to a recording systemdisposed outside the mouth for recording electrical signals produced bythe transducer.

It is yet another object of the invention to provide a method of placinga transducer in an apparatus for recording and measuring in-situ skullvibration, the method comprising the steps of selecting a metallicreceiving means capable of holding said transducer in intimate contactwith said receiving means and at least one teeth; filling said receivingmeans with a dental material capable of filling any gaps between saidreceiving means and said at least one natural tooth, said material beingcapable of setting to a sufficiently rigid state in the undercut area inthe gingival one-third of at least one maxillary tooth and theinterproximal area between two adjacent maxillary teeth, with saidmaterial being able to compress sufficiently to allow the release andremoval of said means from the mouth, said material being capable oftransmitting mechanical vibration within the dental bone conductionpathway to the receiving means and transducer; connecting saidtransducer via a wire to a recording system disposed outside the mouthfor recording electrical signals produced by the transducer.

The receiving means and the filler material constitute a tooth couplingassembly for engaging the transducer in intimate vibrational contactwith at least one teeth and preferably no more than two posterior teethin the upper arch (maxilla). The intimate vibrational contact isachieved through a spring-load created by the coupling assembly.

Optionally, the coupling assembly further comprises a retainer such as ametallic spring clip for biasedly retaining the receiving means in theundercut area in the gingival one-third of at least one maxillary toothand the interproximal area between two adjacent maxillary teeth on boththe buccal and lingual surfaces.

In one embodiment, the tooth coupling assembly comprises a receivingmeans configured like a shell or tray filled with a biocompatible fillermaterial which fills the shell and when placed over the teeth, flows toconform to the teeth, and then hardens. Spring-load is created either bythe external shell or tray, the biocompatible filler material used forcustomization, or in the preferred embodiment, a combination of aspringy tray and (springy) compressible biocompatible filler material.As used herein, the terms, “mouth safe” and “biocompatible materials”are used interchangeably.

In another embodiment, the receiving means of the tooth couplingassembly is preferably a disposable, thin, springy-plastic fabricatedfrom a plastic like PVC. Alternatively it could be a spring-metal designfabricated from a material like Nitinol. Alternatively, it can be a very“rigid” cast metal which, in certain circumstances, provides costadvantages for re-use between different persons after autoclaving.

The biocompatible filler material of the tooth coupling assemblypreferably is a poly-vinyl siloxane (PVS) addition-type dentalimpression material with a hardness durometer of about 40 (Shore-Dscale) such as R-Si-Line Metal Bite (R-dental, Hamburg, Germany). It canalso be a more rigid setting material such as dental impression compound(e.g., Denture Impression Compound, Kerr Manufacturing, Romulus,Mich.)). A preferred embodiment uses PVS because after it has chemicallyset, the PVS has sufficient compressibility to spring over the undercutsof the natural teeth. In addition, PVS can retain its “set memory” anddetail for long periods of time if properly stored (at cool, roomtemperature). When or if dental compound is used instead of PVS, thereceiving means is configured to flex or spring around the toothundercuts. In either case, the tooth coupling assembly allows forrepeatable placement and coupling force against the teeth over longperiods of time, such as six-months or more.

In one embodiment, the transducer-sensor is of the piezoelectric type.Piezoelectric transducer designs of any physical size, sensitivity, andcapability (two-axis, three axis, etc.) can be used with this system.Other types of transducer materials such as magnetostrictive,magnetoresistive, and voice coil are usable by the instant invention.However, to record skull acceleration, piezoelectric transducers iscurrently the most cost effective.

BRIEF DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

In the drawings, wherein like reference numerals identify similarelements:

FIG. 1 is a process flow diagram of the method for recording andmeasuring in-situ skull vibration according to one embodiment of thepresent invention.

FIG. 2 illustrates the various embodiments of the tooth couplingassembly including the receiving means, transducer “side-car”,transducer (accelerometer), and filler materials used for customization.

FIG. 3 illustrates a top-view of tooth coupling assembly including the“side-car”. The transducer and biocompatible filler materials areabsent.

FIG. 4 is a side-perspective view of the tooth coupling assembly withoutthe transducer or the biocompatible filler material.

FIG. 5 illustrates a transducer (accelerometer) with disposable orpermanent mouth-safe covering.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings of the present disclosure in which likenumbers represent the same structure in the various views, FIG. 1 is aprocess flow schematic of the method for recording and measuring in-situskull vibration according to one embodiment of the present invention.Elements 60 and 70 are companion electronic devices that match both thetransducer or sensor 50 and the specific modality employed for recordingskull vibrations. Software installed on the data recording device 70will vary with the type of device (e.g., laptop computer, smartphone,etc.) and the diagnostic situation (e.g., the recordation of vibrationcreated by a tooth or bone oscillator, or natural breath sounds existingwithin the dental bone conduction pathway). The modalities to beemployed are within ready reach of one of skill in the art and it isunderstood that elements 60 and 70 can come in a wide variety of off theshelf configurations.

In a preferred embodiment, the recording software is configured todetermine the in situ level of bone vibration created by skullstimulation from hearing aid systems which stimulates via the teeth.Also in an office or Clinic/hospital setting, where skull stimulationcan occur from a calibrated audiometer bone oscillator, softwarespecific to that audiometer and (hardware) setting can be written. It isalso envisioned that during surgical procedure when an osseointegratedimplant such as the Bone Anchored Hearing Aid (Cochlear Inc., GothenburgSweden) is being placed, initial recording of pure-tones withstimulation of the implant may be taken. Then after several months, theimplant again may be stimulated and recordings made by the Invention,with the objective being to determine the implant stability throughresonant frequency analysis (used in the field of implantology todetermine the level of osseointegration achieved). Thus the particularsoftware and hardware platform may differ depending on the measurementobjective.

Accordingly, because of the repeatability of the instant methodology ofmeasuring and recording in situ skull vibrations, degradation of hearingacuity and clinical changes related to hearing can be diagnosed. Forexample, in a hearing aid using an osseointegrated implant, if theperson reports a decrease in hearing ability—the method of the instantinvention can be used to assess whether the cause is due to a new nervedamage, or rather, damage to the implant or bone. Thus with the instantinvention, the skull stimulation level (skull vibration levels) can becompared over time (through use of the same tooth-coupling assembly),leading to differential diagnosis.

FIG. 2 illustrates the various embodiments of the tooth couplingassembly including the receiving means, transducer “side-car”,transducer (accelerometer), and filler materials used for customization.The preferred embodiment of the tooth coupling assembly is placed overtwo adjoining teeth in the maxillary arch. The first preferred toothcovered is the maxillary first molar, and thus the second tooth coveredwould be the adjacent bicuspid (usually the 2^(nd) bicuspid, also knownas the 2^(nd) premolar). FIG. 2 shows a ‘slice” view of the toothcoupling assembly slicing between the molar and bicuspid. It ispreferred that the tooth coupling assembly be placed over no more thantwo teeth in order to minimize the mass of the assembly and to maintainthe sensitivity of the attached accelerometer to low-amplitude vibrationin the dental bone conduction pathway.

Referring now to FIGS. 2 and 3, the tooth coupling assembly is placedover a tooth (molar) 1, having a cervical neck 2 (that constriction ofan natural tooth which occurs at the point where the enamel meets theroot; in vivo, this landmark is visible at or near the gum-line alongthe length of the tooth at the gum-line; it is an undercut area,relative to the clinical crown of the tooth), and a central groove 3which runs in a mesial to distal, or front-of-mouth to back-of-mouthdirection along the biting surface of the clinical crown usually in thecenter of the occlusal surface. Referring to FIG. 3, the interproximalarea 4 that exists at the gum-line between two adjacent teeth is shown.When one uses dental floss, the floss is intended to clean thebuccal-to-lingual area shown by the interproximal area 4 which is anaturally occurring undercut area above the height of contour or“presumed contact area” between two adjacent teeth.

The tooth coupling assembly 10 is preferably “C” or “U” shaped with theterminal tips engaging the natural undercuts which occur along eachtooth at the cervical neck 2 and to a deeper extent between two teeth atthe interproximal area 4. The tooth coupling assembly comprises areceiving means 20, a pre-attached sidecar 25, optionally an additionalretaining means such as a metal spring-clip 30, a customizing dentalmaterial 40, and a transducer 50. In a preferred embodiment, sidecar 25is integrally formed within the same thermoplastic mold as the receivingmeans 20 (although a different manufacturing process may join the twoelements through bonding, etc.). The metal spring clip 30 is typicallyadded later in fabrication. When fitting or customizing to a patient,the customizing dental material 40 is required.

The preferred material for the receiving means 20 is a thermoplastic orthermosetting polymer which is biocompatible and mouth safe, relativelyrigid, lightweight, and inexpensive. Such plastics are well in the artand include polyvinylchloride (PVC), polyethylene, polystyrene,Polytetrafluoroethylene (PTFE), Polyetheretherketone (PEEK),Ethylene-Vinyl Acetate (EVA), and others thermoplastic or thermosettingreadily available in the art.

The retaining means 30 is preferably a pre-shaped spring-wire made fromone of many orthodontic-types of wire, such wire material containingstainless steel, nickel, titanium, nitinol or alloys thereof.Half-round, square, or rectangular wire (e.g., 0.025×0.020) may be used.As part of the manufacturing or assembly process of the tooth-couplingassembly 10, the wire-clip retaining means 30 is secured to thereceiving means 20 with a mouth-safe glue or bonding material 32 suchthat the wire does not slide. The bonding material 32 thus can functionas the fulcrum of the spring-arms which terminate in 31-b (buccal orcheek side) and 31-l (lingual or tongue side). An example of such anadhesive or bonding dental material 32 is Triad (Dentsply, Inter., York,Pa.). Also, a channel can be made during the thermoforming process ofthe receiving means 20, for fitting the wire-clip 30 into the receivingmeans 20 thereby needing minimal adhesion at 32. (For example, a channelof 0.027″ width and 0.024″ height typically will accommodate a standard,flat rectangular 0.025×0.020 orthodontic wire.)

The customizing dental material 40 can be of one of several kinds ofdental materials including rigid impression compound, polyvinylsiloxane,temporary dental cements, denture pastes, and the like. The materialused to fill the tooth coupling assembly 20 preferably is a poly-vinylsiloxane (PVS) addition-type dental impression material with a hardnessdurometer of about 40 (Shore-D scale) such as R-Si-Line Metal Bite(R-dental, Hamburg, Germany). It can also be a thermoplastic materialsuch as dental impression compound (e.g., Denture Impression Compound,Kerr Manufacturing, Romulus, Mich.). The adhesiveness, hardness, orrigidity of the dental material should be inversely related to therigidity of the thermoplastic of the receiving means 20 plus spring wireclip 30. For example, if the receiving means 20 and the wire clip 30 donot flex easily when placed over teeth 1, then dental material 40 can berelatively more compressible. In this example, polyvinylsiloxane ispreferable over harder dental impression compound because when thetooth-coupling assembly 10 is relatively rigid and does not flex, thenit can only be retrieved from the undercuts at 2 if a compressibledental material is used. By contrast, using a more flexible material forthe receiving means 20 and “softer spring” for the retainer spring 30,then a more rigid material (e.g., dental compound) can be used forcustomizing material 40. It should be clear that by varying thematerials used for the receiving means 20, the spring retainer clip 30,and the customizing filler material 40, different overall mechanicalproperties are achievable for the tooth coupling assembly 10. It isunderstood that different materials can and should be used in order toachieve differing objectives of cost, ease-of-use, ease-of-fabrication,retention, repeatability of placement, and sensitivity (for the selectedaccelerometer 50) without departing from the scope of the invention.

Referring to FIGS. 2 and 3, elements 21 b and 21-l are the area of thereceiving means that engages the natural tooth undercut 2 at the buccal(b) side and the tongue or lingual (l) side respectively. It should beunderstood that areas 21 b and 21 l run the entire mesio-distal lengthor front-of-mouth to back-of-mouth direction of the teeth (two teeth areincluded in 10). Elements 22 b and 22 l are “flanges” that arethermoformed to compliment the compressive areas 21 b and 21 l. The“flanges” are seen more easily in FIGS. 2 and 4. These “flanges” allowthe patient (or dentist) to get their finger or fingernail above thereceiving means 20 and more easily retrieve it from the mouth. Withoutthe flanges 22-b and 22-l, removal of the tooth coupling assembly 10could be difficult, particularly if there is a deep undercut at 2.Element 23 b and 23 l are single points located in the interproximalarea between the two teeth; each is located about half-way between themolar and bicuspid teeth along an imaginary line running along 2 (in amesio-distal or front-of-mouth to back-of-mouth direction), with element2 being that undercut area of teeth that generally is noticeable alongthe gum-line. Element 4 (seen in FIG. 3) is an imaginary line connecting23 b to 23 l. The design elements 21 and 23 are sized and configured tocorrespond to the natural constrictions that occur both at the gum-lineof teeth and between adjacent teeth.

In a preferred embodiment, the tooth coupling assembly 10 also comprisesa side car or transducer docking zone having elements 25, 26, and 27. Asshown in FIG. 2, they are located on the buccal side of the teeth 1. Thetransducer docking zone is shaped and configured to correspond to theshape of the transducer to be received. As shown in FIG. 2 and FIG. 3,this zone has an outer wall 25, a floor 26, and an inner wall 27 whichis also the buccal wall of the receiving means 20. The outer wall 25 isintended to flex and compress in a direction towards the tooth under thepressure of spring-wire retainer 30, or more particularly, 31 b which isthe buccally disposed terminal tip of spring-wire retainer 30. Element31-l, which also has been pre-formed through metal bending, serves toadd to the retention of receiving means 20 (at areas 21-l and 21-b) byreciprocating the force exerted by the tip of the spring 31-b. It isthrough the forcing action of the spring wire retainer 30, thattransducer 50 is pressed intimately and absolutely against the innerwall 27 of the transducer docking zone. Because of this intimate andabsolute contact of the transducer 50 to the receiving means 20, and theabsence of gaps within the tooth coupling assembly 10, low-amplitudevibrations within the dental bone conduction pathway can be sensed andrecorded accurately by transducer 50.

FIG. 3 and FIG. 4 illustrate a top-view and side view respectively oftooth coupling assembly 10 including the “side-car” or transducerdocking zone showing how the tooth coupling assembly is sized, shapedand configured to conform to the natural curvatures and undercuts of themaxillary molar and adjoining bicuspid. The receiving means 20,containing mouth safe plastics or polymers is spring-loaded into theundercut area in the gingival one-third of at least one maxillary toothand the interproximal area between two adjacent maxillary teeth on boththe buccal and lingual surfaces. The mouth safe plastics or polymers ofthe receiving means 20 is at least one selected from the groupconsisting of acrylates, methacrylates, urethanes, polyesters,polyvinylchloride (PVC), polyethylene, polystyrene,polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK),ethylene-vinyl acetate (EVA).

The receiving means 20 is preferably spring-loaded for biased retentioninto the undercut area in the gingival one-third of at least onemaxillary tooth and the interproximal area between two adjacentmaxillary teeth on both the buccal and lingual surfaces and said springload may be achieved by use of mouth safe metals in conjunction with thethermoplastic or thermosetting materials. As an alternative embodiment,the receiving means 20 on the alternative can be rigid and made ofautoclavable and reusable mouth-safe metals selected from the groupconsisting of stainless steel, nickel, chromium, cobalt, titanium, andalloys thereof. The receiving means further comprise flanges 22 b and 22l located in a supra-gingival position relative to the tooth undercutarea in the gingival one-third of at least one maxillary tooth, saidflanges sized and configured for aiding in removing of said means fromthe mouth of a person.

In a preferred embodiment using a springy thermoplastic material,elements 21-l and 21-b and points 23-l and 23-b create retention forcesfor the tooth coupling assembly 10. Particularly useful for theretention of the tooth coupling assembly 10 are points 23-l and 23-bwhich generally conform to the interproximal areas between the two teeth(molar and bicuspid). Because retention in the interproximal area isdesirable, the tooth coupling assembly is designed to include at leasttwo teeth. Furthermore, because there is a natural curvature to eachtooth at the gum-line and there is additional undercut created by twoteeth (at anatomical area 4), a preferred embodiment of this inventionfurther teaches the use of a retainer spring-wire 30 that compresses atpoints 31-l and 31 b thus urging the assembly into undercut area 2 andinterproximal area 4. Thus, spring-wire 30 helps to squeeze thepre-formed thermoplastic receiving means 20 both into the tooth neckalong gum-line and into space between two adjoining teeth, andconcomitantly, urges the transducer 50 towards tooth 1.

In order to facilitate placement and removal, the tooth couplingassembly 10 may be further provided with a handle 29 connected to theassembly 10 via any suitable connection or attachment means 28 such as ascrew, hook, or slottable notch.

Repeatability of placement and in-situ retention of tooth-couplingassembly 10 is achieved through a combination of forces created by thespring force exerted by the thermoformed receiving means at areas 21-l,21-b, and points 23-l, and 23-b; the spring-force exerted by the metalclip 30, specifically at points 31-l and 31-b; and pressure-fit,mechanical-fit, or adhesion, any of which occurs through selection ofthe appropriate dental material 40.

Element 50 is the transducer (accelerometer) which in the preferredembodiment should be slid into a tightly conforming docking zone or“sidecar” 25. The transducer senses mechanical vibrations within thedental bone conduction pathway and transmit a corresponding electricalsignal through a wire 55. Wire 55 connects to a signal conditioning unit60 (e.g., a pre-amplifier) and data recording system 70 (e.g., computeror smart-phone). These elements 60 and 70 are well known to those ofordinary skill in the art of vibration measurement and will vary withboth transducer selection and modality of use. The wire 55 also servesas a safety feature to prevent potential swallowing of the tooth-clip10.

As is generally known, depending on the type of piezoelectric transducerused, the electrical signal from the transducer typically requires ashielded lead-wire, pre-amplifier, and filtering or other signalprocessing. Suitable pre-amplifier design or other companion electronicsnecessary to optimize the signal from a specific transducer-sensor allfall within the scope of this invention.

The transducer of the present invention may be a piezoelectric,magnetostrictive, magnetoresistive, or voice coil effect material. Itcan be a uni-axial (x-axis), bi-axial (x+y-axis) or tri-axial direction(x+y+z-axis) type. It may further comprise an extra-orally disposed wireor string attached to the transducer and/or receiving means.

The type of transducer used depends on the modality and the objective ofrecording skull vibrations via the dental bone conduction pathway. Forexample for cost purposes, one may use a low-cost disposable piezo-filmMEMS type of transducer. For longer-term scientific analysis of a singlehuman's breath-sounds, where the repeatability-of-placement feature ofthe tooth-coupling assembly is important, one may use a highly sensitivetri-axial piezoelectric based transducer (e.g., Model 339A30 fromPCB-Piezotronics, Depew, N.Y.). For the preferred embodiment, alower-cost piezoelectric transducer with high sensitivity in the audiofrequency range can be used, such as Model BU-1774 from KnowlesElectronics (Chicago, Ill.).

It should be obvious that although the transducer 50 is re-useable, itis possible that if a low-cost single-use transducer 50 is available anddesirable, then a mouth-safe glue or other potting material can entirelyencase the transducer 50 within the side-car 25. In this alternativeembodiment, elements 20, 30, and 50 are all pre-assembled by themanufacturer of the tooth-coupling assembly sensor. Final customizationof the assembly occurs through application or use of dental material 40at the time the tooth-coupling assembly is placed in the mouth. Thefinal customization using internal material 40 can be performed byeither a specialist, such as an audiologist, if recording of in-situbone vibration for audiometry is desired, or alternatively,self-customization can occur if one is using the invention as thefront-end sensor in a home sleep apnea study.

In an alternative embodiment for home sleep study if apnea is suspectedor to be diagnosed, then the tooth-clip can be self-customized by theuser through application of a particular and designated dental material40. In this embodiment, the transducer may be pre-assembled along withother external elements of the tooth coupling assembly. The user wouldbe provided with the internal or dental material and instructions forhow to self-fit the assembly over the appropriate teeth. In thisembodiment and application, the recording hardware and software systemobviously would be different than if used by a technician orprofessional in a hospital/clinic setting. In this embodiment andapplication, the sensor is the front-end of a recording system and thedata can be downloaded and remotely analyzed.

FIG. 5 shows the transducer 50 with a covering sheath 58 and safetyconnecting wire 55. Not shown is a plug at the terminal end of 55 thatwould connect into the electronic signal conditioner system 60 withfurther connection to a recording device 70. With a home sleep monitor,for example, this final connection of 60 to 70 can be wireless. That is,in another embodiment element 60 contains a radio transmitter that linksor communicates wirelessly to the recording unit 70. The covering sheath58 may be a disposable sanitary sheath covering the transducer and wire.Preferably sheath 58 is made of a flexible plastic whose thickness isless than 0.5 mm.

In the preferred embodiment transducer 50 is a bi-axial piezoelectricdesign available from one of several manufacturers of suchaccelerometers. The sheath 58 protects the electric transducer from theoral environment, and also if the transducer is to be used acrosspatients, the sheath provides an impermeable and sanitary barrier. Inone embodiment, the sheath 58 is fabricated of disposable thin plastic,and it can extend to cover the safety lead wire 55 to a distance welloutside the mouth. The sheath should tightly fit the transducer 50 andcan be secured with glue (e.g., cyanoacrylate) or alternativelytwist-tied around the safety lead wire 55 and/or the tray handle 29.Alternatively, the sheath can be part of the potting material used tosecure transducer 50 inside the side-car 25, if it is intended that thetooth-coupling assembly contains a disposable, single-use transducer.

The safety lead wire 55 contrasts with wireless systems. While awireless approach is conceptually interesting, the best signal-to-noiseratio is achieved through using a hard-wire connection from the smallsensor to its companion pre-amplifier/signal conditioner. This systemdesign of placing elements 60 and 70 outside the mouth improves comfort,ease-of-use, and safety because the battery and other electroniccomponents of element 60 can be larger and longer-lasting. Besidesimproving comfort of the overall system, this lead wire 55 also providesa safety feature because it mitigates the possibility of swallowing orchoking of the tooth coupling assembly.

The tooth coupling assembly 10 is preferably prefabricated in left-sideand right-side versions, and two or more sizes. By “sizes” it isintended that from a ‘small size” to a “large size” the distance between23-l and 23-b is increased by about 5 millimeters. Either a professional(e.g., audiologist), sleep lab technician (if used in a Clinic basedsleep study) or the user themselves (if used in a at-home sleep study)selects a pre-assemble tooth coupling assembly 10 that contains elements20, 30 and perhaps 50 if there was a low-cost transducer built-in abinitio. The preassembly, however, would not contain transducer 50 if thetransducer was expensive such as a tri-axial accelerometer. After trialin the mouth and determination that the assembly fits snuggly, theperson places the transducer (with its protective sheath) into theside-car 25. Next the user fills the receiving means 20 with the mouthsafe, biocompatible dental material 40 and quickly places into theirmouth, seating it fully before the material sets. The mouth-safe dentalmaterial capable of flowing around all teeth within the receiving meansand then sets to a rigid or semi-rigid state so that no gaps existbetween the teeth and the receiving means. The dental material may beselected from the group consisting of poly-vinyl siloxanes, polyethers,zinc-oxides, dental impression compounds, dental cements, and dentaladhesives. In a preferred case of polyvinyl siloxane (R-Si-Line MetalBite), the setting time would be about 1 minute.

At this point, if the usage of the invention is for a short time such asto measure bone vibration created by a bone oscillator from anaudiometer, then the connecting wire 55 is plugged into the signalconditioner 60 and then connected to the recording system 70. If bycontrast the user will be sleeping with the tooth-coupling assembly allnight, then the customized assembly should be removed and handle 29detached. Since it has been customized, it can be immediately replaced,and if desired, an additional layer of denture adhesive (e.g.,Polygrip,—GlaxoSmithKline Dover, N.J.) added prior to re-seating. Oncethe assembly is seated, the transducer 50 is plugged into the signalconditioner 60 and recording device 70, where at 70 the vibrationswithin the dental bone conduction pathway are recorded, analyzed, ordisplayed (depending upon the hardware/software).

Accordingly, this invention also provides a method of placing atransducer in an apparatus for recording and measuring in-situ skullvibration, the method comprising the steps of selecting a receivingmeans that simultaneously engages the undercut area in the gingivalone-third of at least one maxillary tooth and the interproximal areabetween two adjacent maxillary teeth, engaging said tooth and teeth onboth the buccal and lingual surfaces; filling said receiving means witha dental material capable of filling any gaps between said receivingmeans and said at least one natural tooth, said material being capableof transmitting mechanical vibration within the dental bone conductionpathway to the receiving means and transducer; covering said transducerwith a sheath and placing the covered transducer into said receivingmeans; connecting said transducer via a wire to a recording systemdisposed outside the mouth for recording electrical signals produced bythe transducer. The recording system comprise a signal conditioner,pre-amplifier, amplifier, and electronic data recording device. In oneembodiment, the signal conditioner is linked wirelessly to the saidelectronic data recording device.

The invention also provides a method of placing a transducer in anapparatus for recording and measuring in-situ skull vibration, themethod comprising the steps of selecting a metallic receiving meanscapable of holding said transducer in intimate contact with saidreceiving means and at least one teeth; filling said receiving meanswith a dental material capable of filling any gaps between saidreceiving means and said at least one natural tooth, said material beingcapable of setting to a sufficiently rigid state in the undercut area inthe gingival one-third of at least one maxillary tooth and theinterproximal area between two adjacent maxillary teeth, with saidmaterial being able to compress sufficiently to allow the release andremoval of said means from the mouth, said material being capable oftransmitting mechanical vibration within the dental bone conductionpathway to the receiving means and transducer; connecting saidtransducer via a wire to a recording system disposed outside the mouthfor recording electrical signals produced by the transducer.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present inventionwithout departing from the spirit or scope of the invention.Modification of the above-described assemblies and methods for carryingout the invention, combinations between different variations aspracticable, and variations of aspects of the invention that are obviousto those of skill in the art are intended to be within the scope of theclaims. The drawings here presented are for illustrative purposed onlyand are no necessarily drawn to scale. Thus, it is intended that thepresent invention cover the modifications and variations of thisinvention provided they come within the scope of the appended claims andtheir equivalents. Accordingly, the invention is not limited by theembodiments described above which are presented as examples only but canbe modified in various ways within the scope of protection defined bythe appended patent claims. All references cited in this specificationare herein incorporated by reference in their entireties.

1. An apparatus for measuring and recording skull vibration in situcomprising: a receiving means which simultaneously engages an undercutarea in a gingival one-third of at least one maxillary tooth and aninterproximal area between two adjacent maxillary teeth on both a buccalsurface and a lingual surface within a mouth of a user; a dentalmaterial capable of filling gaps between said receiving means and saidat least one maxillary tooth, said dental material capable oftransmitting mechanical vibration within a dental bone conductionpathway to said receiving means; a transducer coupled to said receivingmeans, said transducer capable of transducing mechanical vibrationwithin the dental bone conduction pathway into electrical signals; andrecordation hardware and software capable of receiving and processingsaid electrical signals from said transducer.
 2. The apparatus of claim1, further comprising a metallic spring for biasedly retaining thereceiving means in the undercut area in the gingival one-third of atleast one maxillary tooth and the interproximal area between twoadjacent maxillary teeth on both the buccal and the lingual surfaces. 3.The apparatus of claim 2, wherein said metallic spring is configuredfrom orthodontic spring wire containing stainless steel, nickel,titanium, or alloys of stainless steel, nickel or titanium.
 4. Theapparatus of claim 1, wherein said receiving means is spring-loaded intothe undercut area in the gingival one-third of at least one maxillarytooth and the interproximal area between two adjacent maxillary teeth onboth the buccal and the lingual surfaces and wherein said receivingmeans contains a mouth safe polymer.
 5. The apparatus of claim 4,wherein the mouth safe polymer is selected from the group consisting ofacrylates, methacrylates, urethanes, polyesters, polyvinylchloride(PVC), polyethylene, polystyrene, polytetrafluoroethylene (PTFE),polyetheretherketone (PEEK), and ethylene-vinyl acetate (EVA).
 6. Theapparatus of claim 1, wherein said receiving means is spring-loaded forbiased retention into the undercut area in the gingival one-third of atleast one maxillary tooth and the interproximal area between twoadjacent maxillary teeth on both the buccal and the lingual surfaces andwherein said receiving means is made of a mouth-safe metal.
 7. Theapparatus of claim 1, wherein said receiving means is rigid and is madeof autoclavable and reusable mouth-safe metal.
 8. The apparatus of claim6 or 7, wherein the mouth safe metal is selected from the groupconsisting of stainless steel, nickel, chromium, cobalt, titanium, andalloys of stainless steel, nickel, chromium, cobalt or titanium.
 9. Theapparatus of claim 1, wherein said receiving means comprises flangeslocated in a supra-gingival position relative to the undercut area inthe gingival one-third of at least one maxillary tooth, said flangesconfigured for aiding in removal of said apparatus from the mouth of theuser.
 10. The apparatus of claim 1, wherein said receiving means isfilled with a mouth-safe dental material capable of flowing around teethwithin the receiving means and setting to a rigid or semi-rigid state.11. The apparatus of claim 10, wherein said dental material is selectedfrom the group consisting of a poly-vinyl siloxane, a polyether, azinc-oxide, a dental impression compound, a dental cement, and a dentaladhesive.
 12. The apparatus of claim 1, wherein said transducercomprises a piezoelectric, a magnetostrictive, a magnetoresistive, or avoice coil effect material.
 13. The apparatus of claim 1, wherein saidtransducer is one of a uni-axial transducer, a bi-axial transducer, or atri-axial transducer.
 14. The apparatus of claim 1, further comprisingan extra-orally disposed wire attached to at least one of saidtransducer or said receiving means.
 15. The apparatus of claim 1,further comprising a disposable sanitary sheath covering saidtransducer.
 16. The apparatus of claim 15, wherein the sheath is made ofa flexible plastic having a thickness of less than about 0.5 mm.
 17. Amethod of placing a transducer in an apparatus for recording andmeasuring in-situ skull vibration, the method comprising the steps of:(a) selecting a receiving means that simultaneously engages an undercutarea in a gingival one-third of at least one maxillary tooth and aninterproximal area between two adjacent maxillary teeth, therebyengaging said at least one maxillary tooth and said two adjacentmaxillary teeth on both a buccal surface and a lingual surface within amouth of a user, wherein a transducer is coupled to said receivingmeans, said transducer capable of transducing mechanical vibrationwithin a dental bone conduction pathway into electrical signals; (b)filling said receiving means with a dental material capable of fillinggaps between said receiving means and said at least one maxillary tooth,said material being capable of transmitting mechanical vibration withinthe dental bone conduction pathway to the receiving means and saidtransducer; (c) covering said transducer with a sheath, and placing thecovered transducer into said receiving means; (d) connecting saidtransducer via a wire to a recording system disposed outside of themouth of the user for recording the electrical signals produced by thetransducer.
 18. The method of claim 17, wherein said apparatus comprisesa signal conditioner, a pre-amplifier, an amplifier, and an electronicdata recording device.
 19. The method of claim 18, wherein said signalconditioner is linked wirelessly to said electronic data recordingdevice.
 20. The method of claim 17, wherein the receiving means containsan encapsulated transducer ab initio.
 21. A method of placing atransducer in an apparatus for recording and measuring in-situ skullvibration, the method comprising the steps of: (a) selecting a metallicreceiving means capable of holding said transducer in intimate contactwith said receiving means and at least one tooth; (b) filling saidreceiving means with a dental material capable of filling gaps betweensaid receiving means and said at least one tooth, said material beingcapable of setting to a sufficiently rigid state in an undercut area ina gingival one-third of at least one maxillary tooth and aninterproximal area between two adjacent maxillary teeth, said materialbeing able to compress sufficiently to allow for release and removal ofsaid receiving means from a mouth of a user, said material being capableof transmitting mechanical vibration within a dental bone conductionpathway to the receiving means and the transducer; (c) connecting saidtransducer via a wire to a recording system disposed outside the mouthfor recording electrical signals produced by the transducer.